The present invention relates to a pedestrian protection device for a motor vehicle, comprising a crossmember, in particular a bumper crossmember, and a deformation element, which is arranged in front of the crossmember.
A known front end of a motor vehicle has, for example, a bumper crossmember which is fastened to front ends of longitudinal members or crash boxes, and a bumper cladding. A foam which is deformable at a comparatively low load level is arranged between the bumper cladding and the bumper crossmember in order to protect pedestrians. By this means, in the event of a collision of the motor vehicle with a pedestrian, the pedestrian is protected against direct and immediate collision with a stiff structure, such as the bumper crossmember, located therebehind. The deformable foam has an effect in respect of pedestrian protection in particular within a certain speed range, such as, for example, 20 to 50 km/h.
Furthermore, it is required for the motor vehicle to remain free from damage in a collision in a very low speed range of up to, for example, 4 km/h, in which the pedestrian protection is irrelevant because of the low speed.
Furthermore, at a somewhat higher speed, for example less than 20 km/h, which is likewise still not relevant for pedestrian protection, it is required that damage during a collision be as small as possible and, for example, a radiator structure which is located in the front end region is not to be damaged.
In the event of a collision at a comparatively high speed which is no longer relevant for pedestrian protection, a focus is on designing the motor vehicle and the crash structure thereof for occupant protection. For this purpose, the front end or vehicle front is designed in such a manner that it is deformed in an energy-absorbing manner over a certain deformation distance.
However, the requirements imposed on pedestrian protection are partially contradictory with the requirements at lower or higher speeds. This contradiction can, however, basically be solved by a comparatively long vehicle overhang. However, the long vehicle overhang leads to a greater overall length of the vehicle and also to a higher weight of the vehicle. Furthermore, driving dynamics of the vehicle are disadvantageously affected by the long vehicle overhang.
In order to solve the resulting conflicting objectives, a bumper arrangement with a crossmember which is fastened to the vehicle body via crash boxes has been proposed, for example, in DE 102010054641 A1. A pedestrian protection element for soft impact of a pedestrian is formed in front of the crossmember in the direction of travel. In addition, a pivotable energy absorption element is provided which is pivotable in front of the pedestrian protection element and thereby permits increased energy absorption in collisions in which a higher collision energy absorption capability of the crash structure of the motor vehicle is required.
DE 102012112636 A1 likewise shows a bumper arrangement, including a bumper crossmember and a pedestrian protection element which can be switched over by means of an actuator from a stiff state into a comparatively soft state which serves for pedestrian protection.
A common feature of the bumper arrangements described in DE 102010054641 A1 and DE 102012112636 A1 is that a crash or pre-crash sensor system is required for this purpose, wherein, on the basis of the output signals of the sensor system, a switch can be made between a hard stiff state of the crash structure with high collision energy absorption capability and a soft state of the crash structure with low collision energy absorption capability for the benefit of pedestrian protection.
It is the object of the present invention to provide a pedestrian protection device comprising a bumper crossmember and a deformation element, which is arranged in front of the bumper crossmember, which pedestrian protection device is constructed in a simple manner and is switchable between different rigidities and/or strengths independently of a sensor system or an actuator.
This and other objects are achieved by a pedestrian protection device for a motor vehicle in accordance with embodiments of the invention.
A pedestrian protection device for a motor vehicle, in particular for a front of the motor vehicle, has a crossmember, in particular a bumper crossmember, and a deformation element, which is arranged in front of the crossmember. The deformation element has a bending limb, the end of which lies against a surface or, in the event of a collision, in particular a head-on collision, of the motor vehicle comes to bear against the surface. The end of the bending limb is designed to be displaceable along the surface as a result of the collision, wherein the surface has a latching device with which the end of the bending limb is in particular latchable.
According to the present invention, it is therefore possible for a rigidity of the deformation element to be increased by the bending limb latching into place during deformation of the deformation element as a result of the collision, without a collision sensor system or an actuator system being required here. The collision load itself therefore brings about a stiffening of the deformation element.
The term latchable into place is used in the sense of a form-fitting engagement of the end of the bending limb with the latching device.
Within the context of the invention, the term pedestrian also includes other traffic participants or non-occupants, for example cyclists. Accordingly, the device could also be called non-occupant protection device.
The end of the bending limb is in particular a free end of the bending limb.
The specification “in front of the crossmember” means in particular that the deformation element is arranged on an outer side of the crossmember, i.e. a side of the crossmember that faces an outer skin of the body, for example in the form of a bumper cladding. Furthermore, the outer side of the crossmember can be the side which faces the direction from which a collision load can be anticipated.
According to a preferred development of the present invention, the bending limb, the end of the bending limb, the surface and the latching device are designed in an interacting manner such that, in the event of a collision impulse which is smaller than a predetermined collision impulse or collision impulse threshold value, the end of the bending limb latches with the latching device, and, in the event of a collision impulse which is equal to or greater than the predetermined collision impulse or collision impulse threshold value, the end of the bending limb does not latch with the latching device, and in particular passes or jumps over the latching device, and is therefore displaceable further. In particular, in the latter case, the end of the bending limb can be displaceable or shiftable further along the surface.
Therefore, with simple means and using the collision impulse, the deformation element can have a less stiff, soft state, in which the bending limb or the end of the bending limb is not latched into place, or a stiffer, hard state, in which the end of the bending limb is latched into place, depending on the collision impulse. According to a preferred development of the pedestrian protection device, in the event of a collision, when the front end of the bending limb is latched into place, the deformation element is deformable at a higher force level or undergoes brittle failure in the event of the higher force level, wherein, when the front end of the bending limb is latched into place, the deformation element is deformable at a higher force level or undergoes brittle failure at a higher force level.
The surface is preferably arranged substantially transversely with respect to a (main) collision direction or at least parallel to a vertical direction of the vehicle. In particular, the surface can be arranged substantially transversely with respect to a main driving direction of the motor vehicle. As an alternative definition, the displacement direction of the end of the bending limb runs transversely, preferably substantially perpendicularly, with respect to a collision direction. The collision direction is the direction from which a collision load from a collision counterpart should be expected.
The surface can be a flat surface. However, the surface can also have a different shape. For example, the surface can have a step in the region of the latching device. The surface can also be corrugated in a suitable manner.
Furthermore, the surface can have an activation slope at a point between the end of the bending limb and the latching device, the activation slope supporting the end of the bending limb here in that, from the predetermined collision impulse, said end jumps over the latching device and permits deformation of the deformation element at a low load level.
The surface can be formed on the crossmember or on a part mounted on the crossmember. The surface can be, for example, part of the crossmember. In particular, the surface can be formed in a closing plate of a profiled crossmember.
The deformation element can be of substantially arcuate and/or U-shaped and/or V-shaped design or the like.
The deformation element can be formed integrally from a deformed sheet. A deformation element of this type can easily be produced, is cost-effective and can have a low weight. However, the deformation element can also consist of a plurality of parts which are connected to one another.
Furthermore, the bending limb can be connected to the deformation element in an articulated manner.
A plurality of deformation elements can be arranged spaced apart from one another in the transverse direction of the vehicle in front of the crossmember. The collision-dependent deformation effect can therefore be achieved over an entire extent of the crossmember. However, a plurality of deformation elements can also be connected to form one deformation element. A deformation element of this type correspondingly has a plurality of bending limbs. This facilitates installation.
According to a preferred embodiment, the depression can be a groove. A groove can be formed simply and cost-effectively in a crossmember. For example, the groove can run along the crossmember in the transverse direction of the vehicle substantially over an entire width of the crossmember.
The deformation element can have a length of 50 to 150 mm, preferably 70 to 110 mm, in the collision direction and/or longitudinal direction. This length is relevant in particular for pedestrian protection.
The deformation element is preferably arranged between the crossmember and a body outer skin, for example a bumper cladding. A deformation region of the deformation element is formed between the crossmember and the body outer skin. The deformation element can therefore directly affect its action in the event of the collision.
The deformation element is preferably formed from steel or aluminum or an aluminum alloy, but can also be formed from a fiber-reinforced plastic.
Abovementioned developments of the inventions can be combined as desired with one another insofar as possible and expedient.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.